Passengers aboard the Carnival Triumph could have been selfish and looked out only for themselves and their loved ones after their cruise ship lost power. Instead, they became comrades in a long, exhausting struggle to get home.

As ship conditions deteriorated after an engine fire, travellers formed Bible study groups, shared or traded precious supplies and even welcomed strangers into their private cabins. Long after they've returned to the everyday luxuries of hot showers and cold drinks, passengers said, they will remember the crew and the personal bonds formed during a cruel week at sea.

The tired tourists finally reached land on Friday and gave a glimpse into the intensely uncomfortable journey they had endured.

Sandy Jackson was fortunate to have an upper-level room with a balcony and a breeze that kept the air in her cabin fresh. Rooms on the lower decks were too foul or stifling, so Jackson took in five people, including four strangers.

"We knew one, the others we're very good friends with now," Jackson said. "Everyone was very cordial in sharing supplies. What you had and they didn't have, everyone shared as much as possible."

Brandi Dorsett said people were antsy and irritable at times, and there was tension. But it never got out of hand.

"People were bartering. Can I have your cereal for this? Can I have your drink for that?" she said. "We had one lady, she was begging for cigarettes for diapers. There were no diapers on the boat. There was no formula on the boat."

The ship left Galveston, Texas, on February 7 for a four-day jaunt to Cozumel, Mexico. The fire paralysed the ship early on Sunday, leaving it adrift in the Gulf of Mexico until tugboats towed the massive 14-storey vessel to Mobile. It arrived to cheers and flashing cameras. Passengers had to wait several more hours to disembark.

Many of the more than 4200 people aboard were bused to New Orleans to catch a flight home or to the ship's home port in Galveston. And as if they hadn't suffered enough, one of the buses broke down during the two-hour ride to New Orleans. Passengers on a different bus reported losing their luggage.

But that was nothing compared to life on the crippled cruise liner. To pass the time, Joseph Alvarez said about 45 people gathered in a public room on the lower deck for Bible study.

"It was awesome," he said. "It lifted up our souls and gave us hope that we would get back."

Because many passengers were sleeping on the outside deck, Dwayne Chapman used his pocket knife to cut decorative rope to make tents out of bed sheets. At first, other passengers told him they thought he was going to get in trouble, but later, everyone wanted to borrow his knife to do the same thing.

"The first thing we did was open up those Diet Cokes and we drank some," McIntosh said.

Tugs pulled the ship away from the dock on Friday (local time), moving it down a waterway to a shipyard where it will be repaired. Carnival spokesman Vance Gulliksen said the damage assessment was ongoing.

The cleanup seemed daunting. Passengers described water-logged carpet, sewage seeping through the walls, overflowing toilets and a stench so bad people choked when they tried to endure it.

But by most accounts, the crew did as much as they could, using disinfectant and picking up plastic bags of faeces after toilets stopped working.

David Glocker, of Jacksonville, Florida, praised the crew's efforts to help passengers and recognised the conditions for them were worse than for most passengers because their quarters were on the lowest part of the ship.

"The conditions down there were horrible. They all had to wear masks," he said. "They worked their butts off trying to get us food."

Dorsett praised a voice over the ship's public address system that she knew as "Jen".

"Jen was fabulous. I can remember her saying 'everything is brilliant'," Dorsett said. "One day, she was just talking and she said, 'I know, folks, it just really sucks'. So she was even letting go. She would try to keep that happy spirit, but yet sometimes you could hear tension in her."

Six investigators from the National Transportation Safety Board were in Mobile to look into the cause of the engine-room fire, which happened some 242kms off Mexico's Yucatan Peninsula.

NTSB spokesman Keith Holloway said the agency was working with the Coast Guard and the Bahamas Maritime Authority, which will serve as the primary investigative agency.

The Bahamian government was taking the lead because the Triumph is a Bahamian-flagged vessel, and it was in international waters at the time of the fire, Holloway said.

Passengers described a horrifying scene after the fire. Some said they smelled smoke and received conflicting instructions about every 15 minutes over the PA system. Others ran for lifeboats.

No one was hurt in the fire, and just two people were taken off the ship for medical conditions as a precaution.

Connie Ede was on the cruise with her husband. During the fire, the two got their life jackets ready and put cellphones, passports, money and credit cards in their pockets.

"All in all, I wish it hadn't happened, but it did, and we survived," she said.

Carnival promised to give refunds, offer passengers another trip and cover their transportation costs home. Travellers were also to receive $500 in compensation.

But those gestures may not be enough. Less than 24 hours after the boat docked, the first lawsuit was filed against Carnival Corp. by passenger Cassie Terry, who said she feared for her life and worried about falling seriously ill from the raw sewage and spoiled food. Her complaint seeks unspecified damages.

Maritime attorneys say it's difficult but not impossible to win a case unless the plaintiff can show actual injury or illness.

Carnival chief executive Gerry Cahill apologised at a news conference and again on the PA system as people disembarked.

"I appreciate the patience of our guests and their ability to cope with the situation. ... I know the conditions on board were very poor," he said. "We pride ourselves on providing our guests with a great vacation experience, and clearly we failed in this particular case."